A prospective case control study was conducted in 859 diabetic proband
s and 1059 nondiabetic controls, These were interviewed for history of
diabetes mellitus among their first degree relatives. The protocol al
so included second and third degree relatives, The pre valence of diab
etes mellitus in the first degree relatives of cases and controls show
ed a statistically significant difference (Z=6.7564 and P=0.00000). Si
milarly, the prevalence of diabetes among the second and third degree
relatives of cases and controls differed significantly (Z=2.74 P=0.006
). There were 445 non-insulin dependent diabetes mellitus (NIDDM) and
414 insulin dependent diabetes mellitus (IDDM) in the diabetic proband
s, There was more family history of diabetes mellitus among the first
degree relatives of NIDDM than IDDM and the difference is statisticall
y significant (Z=4.076, P=0000). The second and third degree relatives
of NIDDM and IDDM also differed significantly (Z=4.05, P=00005), This
study indicates that heredity plays an important role in the genesis
of diabetes mellitus in Ethiopian diabetics.